Deep Brain Stimulation May Benefit Advanced Parkinson's Disease Patients, But With Increased Adverse Event Risk

Deep brain stimulation treatment may improve movement skills and quality of life for patients with advanced Parkinson's disease (PD) over other medical therapies, though it may also have a higher risk of serious adverse events, according to an article released on January 6, 2008 in JAMA.



Parkinson's disease is a degenerative disorder affecting motor abilities, and deep brain stimulation is a surgical intervention that is often used when PD complications are not able to be managed with medications. Specifically, the stimulation involves the implantation of electrodes to stimulate specific parts of the brain. There are some effects of this treatment that are not well known, note the authors: "... recent reports highlighting unexpected behavioral effects of
stimulation suggest that deep brain stimulation, while improving motor
function, may have other less desirable consequences," they write. They additionally note that very few randomized trials examine comparative treatments, and many studies exclude older patients.



To investigate the comparative effects of medical and surgical therapies for patients with PD, Frances M. Weaver, Ph.D., of Hines VA Hospital, Hines, Ill., and colleagues performed a randomized controlled trial on patients with PD. The patients came from a variety of age groups, with 25% of the population aged 70 or more. Each participant was randomized to one of three groups. The first received bilateral deep brain stimulation with electrodes stimulating the subthalmic nucleus (n = 60). The next received bilateral deep brain stimulation with electrodes stimulating the globus pallidus (n = 61). The last group received the best medical therapy, including medicine and nonpharmacological therapy such as physical, occupational, and speech therapy, managed by movement disorder neurologists.





At six months, patients provided deep brain stimulations gained an average 4.6 hours each day of time without troubling dyskinesia -- that is, an increase in time when symptoms were in control and motor function was largely unimpeded. In contrast, the best medical therapy group had an average change of zero hours. In the deep brain stimulation groups, motor function also improved significantly with 71% experiencing clinically meaningul motor functions after six months, and only 3% experincing clinically worsening scores. In contrast, in medical therapy patients, 32% showed improvement at six months while 21% showed clinically worsening scores. Patients in the deep brain stimulation group also underwent significant improvement in summary quality of life measures as well as in seven of eight PD specific quality of life scales, in comparison to patients in the best medical therapy group.



However, patients in the deep brain stimulation groups were at 3.8 times the risk of a serious adverse event in comparison with the best medical treatment group. In all, 49 deep brain stimulation patients (40%) experienced 82 serious adverse events. In contrast, 15 best medical therapy patients (11%) experienced 19 serious adverse events. The most common serious adverse event was surgical site infection, while others included nervous system disorders, psychiatric disorders, cardiac disorders, and complications related to the device itself.



The authors point out that the adverse effects of this therapy must be investigated further. "The clinical significance of the adverse events and minor neurocognitive changes observed in patients in the deep brain stimulation group and, more importantly, whether patients who undergo deep brain stimulation view improvement in motor function and quality of life as outweighing adverse events, remain to be explored. More detailed analyses of adverse events and neurocognitive functioning following the conclusion of phase 2 of this study will shed light on these issues. Caution should be exercised, however, against overstating or understating the risks of deep brain stimulation for patients with PD. Physicians must continue to weigh the potential short-term and long-term risks with the benefits of deep brain stimulation in each patient," they write.



Günther Deuschl, M.D., Ph.D., of the Universitätsklinikum Schleswig-Holstein, Kiel, Germany, contributed an accompanying editorial in which he comments on these findings.



"Although deep brain stimulation is the most important innovation for treatment of advanced PD since the discovery of levodopa [drug used to treat PD], many questions are still unanswered. For instance, the optimal timing for the implantation is unknown. The majority of patients undergo deep brain stimulation surgery more than 10 years after disease onset when the patients are already incapable of working and when the disease-related psychosocial decline has already begun. As quality of life is improved with this treatment it may improve psychosocial functioning in general for these advanced stages. With the aging of the general population, PD will become even more common and patients with PD will get older. Therefore, the present results showing similar efficacy and tolerability of deep brain stimulation in younger and older patients must be replicated because it is at variance with some other reports demonstrating lower rates of operative and postoperative complications in younger patients."



"Overall the results of this important study by Weaver et al have convincingly confirmed the 6-month efficacy of deep brain stimulation for advanced PD in the largest patient group studied thus far. However, this study, along with previous research on this therapy, shows that such progress cannot be made without costs in terms of adverse effects."



Bilateral Deep Brain Stimulation vs Best Medical Therapy for Patients With Advanced Parkinson Disease: A Randomized Controlled Trial

Frances M. Weaver; Kenneth Follett; Matthew Stern; Kwan Hur; Crystal Harris; William J. Marks Jr; Johannes Rothlind; Oren Sagher; Domenic Reda; Claudia S. Moy; Rajesh Pahwa; Kim Burchiel; Penelope Hogarth; Eugene C. Lai; John E. Duda; Kathryn Holloway; Ali Samii; Stacy Horn; Jeff Bronstein; Gatana Stoner; Jill Heemskerk; Grant D. Huang; for the CSP 468 Study Group

JAMA. 2009;301(1):63-73.

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Neurostimulation for Parkinson Disease

GГјnther Deuschl

JAMA. 2009;301(1):104-105.

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Anna Sophia McKenney

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